Honduran police said there were no signs of any links to last week's suicide bombings and shootings in Paris that killed 129 people. Islamic State claimed responsibility for the attacks.

The five were part of a wider group of seven Syrian nationals who acquired forged passports in Brazil and then went by land to Argentina on their way north, a U.S. government source familiar with the case said. The source also said there was no evidence to suggest the men were militants.

See photos of the men detained in Honduras:

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Honduras detains Syrians bound for US with doctored Greek passports

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Honduras says Syrians not part of terror cell, want refuge in U.S

Honduran policemen escort one of five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

Honduran policemen escort one of five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

Honduran policemen escort one of five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

Honduran policemen escort one of five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

Honduran policemen escort five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

A Honduran policeman (L background) stands next to four of five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

View of two of five Syrian citizens arrested at the Tocontin international airport in Tegucigalpa on November 18, 2015. Honduran authorities have arrested five Syrians intending to make it to the United States with stolen Greek passports, triggering alarm Wednesday in the wake of the Paris attacks launched by Syria-linked jihadists. AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)

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They took advantage of the porous Triple Frontier near well-traveled tourist destination Iguazu Falls where Brazil, Argentina and Paraguay meet, the source said. The three countries belong to the Mercosur customs bloc, where you can cross borders with simple identity documents rather than passports.

"They probably spent the majority of their time in Brazil, because that's where they got the documents. They made their way from Brazil through Argentina pretty quickly," the U.S. government source told Reuters. "There's a human smuggling cell that is moving people through the region."

Five of the men were detained late on Tuesday in the Honduran capital, Tegucigalpa, on arrival from Costa Rica, police said. They said passports had been doctored to replace the photographs with those of the Syrians.

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They arrived in Brazil from Turkey about a week ago, the U.S. government source said.

A Honduran official said the five men detained there had spent several days in Costa Rica before flying into Honduras.

A sixth man was turned away from Honduras on Friday on arrival by plane from El Salvador, and was sent back. In Paraguay, police detained a seventh Syrian man who was traveling on a stolen Greek passport.

The source said that the Syrian detained in Paraguay was caught because his fake passport was missing some of the vaccinations required.

"They made it through and these are the ones we caught. We got lucky on these guys. Think about the ones we didn't' catch. It's a huge concern," the source said.

Separately, members of two Syrian families turned themselves in to U.S. authorities in Laredo, Texas, at the Mexican border, U.S. Homeland Security officials said on Thursday.

The Department of Homeland Security said two men, two women and four children "presented themselves" at the port of entry and were taken into custody by Border Patrol agents before being handed over to immigration officials for processing.

RELATED: See recent raids across Europe in response to the Paris attacks

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Anti-terrorism raids and arrests across Europe after Paris attacks

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Honduras says Syrians not part of terror cell, want refuge in U.S

BRUSSELS, BELGIUM - DECEMBER 29: Security forces of Belgium stand guard as two people arrested on suspicion of terrorism in Brussels, Belgium on December 29, 2015. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)

BRUSSELS, BELGIUM - DECEMBER 29: Security forces of Belgium stand guard as two people arrested on suspicion of terrorism in Brussels, Belgium on December 29, 2015. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)

PARIS, FRANCE - NOVEMBER 20: On the street where the raid took place in the Saint Denis area of Paris, and where three people died, including the ringleader of the terrorist attack, police man the security barrier as the investigation at the apartment continues. A third body was found in the rubble today. (Photo by Carolyn Cole/Los Angeles Times via Getty Images)

ALSDORF, GERMANY - NOVEMBER 17: Heavily-armed members of the German SEK special forces police unit stand outside a house in Schaufenberger Strasse street where they possibly made two arrests on November 17, 2015 in Alsdorf, Germany. Police announced earlier today that a unit of the SEK special forces had in a separate incident arrested two men and one woman at 9:30 this morning in connection with the recent terror attacks in Paris in the parking lot of a Jobcenter employment office. So far it is unclear who the suspects are though initial reports indicate Salah Abdeslam, a brother of a man who took part in the attacks and whom police are searching for across Europe, is not among them. (Photo by Sascha Steinbach/Getty Images)

ALSDORF, GERMANY - NOVEMBER 17: Heavily-armed members of the German SEK special forces police unit stand outside a house in Schaufenberger Strasse street where they possibly made two arrests on November 17, 2015 in Alsdorf, Germany. Police announced earlier today that a unit of the SEK special forces had in a separate incident arrested two men and one woman at 9:30 this morning in connection with the recent terror attacks in Paris in the parking lot of a Jobcenter employment office. So far it is unclear who the suspects are though initial reports indicate Salah Abdeslam, a brother of a man who took part in the attacks and whom police are searching for across Europe, is not among them. (Photo by Sascha Steinbach/Getty Images)

Policemen check the identity of motorists as part of security measures set following terrorist attacks in Paris on November 17, 2015 at the French-Belgium border in Neuville-en-Ferrain. AFP PHOTO PHILIPPE HUGUEN (Photo credit should read PHILIPPE HUGUEN/AFP/Getty Images)

ALSDORF, GERMANY - NOVEMBER 17: Police officers arrive at Schaufenberger Strasse street where they possibly made two arrests on November 17, 2015 in Alsdorf, Germany. Police announced earlier today that a unit of the SEK special forces had in a separate incident arrested two men and one woman at 9:30 this morning in connection with the recent terror attacks in Paris in the parking lot of a Jobcenter employment office. So far it is unclear who the suspects are though initial reports indicate Salah Abdeslam, a brother of a man who took part in the attacks and whom police are searching for across Europe, is not among them. (Photo by Sascha Steinbach/Getty Images)

Police officers patrol at the main railway station in Berlin, on November 17, 2015. Security has been tightned in Germany following the string of coordinated attacks in and around Paris late November 13, 2015 left at least 129 people dead, in the worst such violence in France's history. AFP PHOTO / DPA / KAY NIETFELD +++ GERMANY OUT +++ (Photo credit should read KAY NIETFELD/AFP/Getty Images)

ALSDORF, GERMANY - NOVEMBER 17: Police officers arrive at Schaufenberger Strasse street where they possibly made two arrests on November 17, 2015 in Alsdorf, Germany. Police announced earlier today that a unit of the SEK special forces had in a separate incident arrested two men and one woman at 9:30 this morning in connection with the recent terror attacks in Paris in the parking lot of a Jobcenter employment office. So far it is unclear who the suspects are though initial reports indicate Salah Abdeslam, a brother of a man who took part in the attacks and whom police are searching for across Europe, is not among them. (Photo by Sascha Steinbach/Getty Images)

Policemen check the identity of motorists as part of security measures set following terrorist attacks in Paris on November 17, 2015 at the French-Belgium border in Neuville-en-Ferrain. AFP PHOTO PHILIPPE HUGUEN (Photo credit should read PHILIPPE HUGUEN/AFP/Getty Images)

Belgium special force officers us a camera as they prepare to enter a house in the Rue Delaunoy in Molenbeek-Saint-Jean of Brussels, on November 16, 2015, several days after a series of deadly attacks on the French capital Paris. During the weekend searches were carried out and multiple people were arrested in relation to the November 13 attacks in Paris which left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/DIRK WAEM =BELGIUM OUT= (Photo credit should read DIRK WAEM/AFP/Getty Images)

Belgium special force officers prepare to enter a house in the Rue Delaunoy in Molenbeek-Saint-Jean of Brussels, on November 16, 2015, several days after a series of deadly attacks on the French capital Paris. During the weekend searches were carried out and multiple people were arrested in relation to the November 13 attacks in Paris which left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/DIRK WAEM =BELGIUM OUT= (Photo credit should read DIRK WAEM/AFP/Getty Images)

Belgium special force officers climb the outside of a house as they prep[are to enter in the Rue Delaunoy in Molenbeek-Saint-Jean of Brussels, on November 16, 2015, several days after a series of deadly attacks on the French capital Paris. During the weekend searches were carried out and multiple people were arrested in relation to the November 13 attacks in Paris which left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/DIRK WAEM =BELGIUM OUT= (Photo credit should read DIRK WAEM/AFP/Getty Images)

Police officers look on as an operation takes place in the Molenbeek district of Brussels on November 16, 2015. Belgian police launched a major new operation in the Brussels district of Molenbeek, where several suspects in the Paris attacks had previously lived, AFP journalists said. Armed police stood in front of a police van blocking a street in the run-down area of the capital while Belgian media said officers had surrounded a house. Belgian prosecutors had no immediate comment. AFP PHOTO / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)

A member of the special police forces takes a picture outside a house being searched in the Rue Delaunoy in Brussels on November 16, 2015. During the weekend searches were carried out and multiple people were arrested in relation to Friday's terrorist attacks in Paris. Several terrorist attacks in Paris, France, have left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/BENOIT DOPPAGNE (Photo credit should read BENOIT DOPPAGNE/AFP/Getty Images)

Security forces personnel walk past during ongoing operations in the Molenbeek district of Brussels on November 16, 2015. Belgian police launched a major new operation in the Brussels district of Molenbeek, where several suspects in the Paris attacks had previously lived, AFP journalists said. Armed police stood in front of a police van blocking a street in the run-down area of the capital while Belgian media said officers had surrounded a house. Belgian prosecutors had no immediate comment. AFP PHOTO / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)

Police escort a woman away from the scene as an operation takes place in the Molenbeek district of Brussels on November 16, 2015. Belgian police launched a major new operation in the Brussels district of Molenbeek, where several suspects in the Paris attacks had previously lived, AFP journalists said. Armed police stood in front of a police van blocking a street in the run-down area of the capital while Belgian media said officers had surrounded a house. Belgian prosecutors had no immediate comment. AFP PHOTO / BELGA / BENOIT DOPPAGNE (Photo credit should read BENOIT DOPPAGNE/AFP/Getty Images)

Heavily armed special forces stand guard outside a house being searched in the Rue Delaunoy in Brussels on November 16, 2015. During the weekend searches were carried out and multiple people were arrested in relation to Friday's terrorist attacks in Paris. Several terrorist attacks in Paris, France, have left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/DIRK WAEM (Photo credit should read DIRK WAEM/AFP/Getty Images)

Police officers man a cordon as an operation takes place in the Molenbeek district of Brussels on November 16, 2015. Belgian police launched a major new operation in the Brussels district of Molenbeek, where several suspects in the Paris attacks had previously lived, AFP journalists said. Armed police stood in front of a police van blocking a street in the run-down area of the capital while Belgian media said officers had surrounded a house. Belgian prosecutors had no immediate comment. AFP PHOTO / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)

Heavily armed special forces stand guard outside a house being searched in the Rue Delaunoy in Brussels on November 16, 2015. During the weekend searches were carried out and multiple people were arrested in relation to Friday's terrorist attacks in Paris. Several terrorist attacks in Paris, France, have left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/BENOIT DOPPAGNE (Photo credit should read BENOIT DOPPAGNE/AFP/Getty Images)

Special force officers move into position outside a house being searched in the Rue Delaunoy in Brussels on November 16, 2015. During the weekend searches were carried out and multiple people were arrested in relation to Friday's terrorist attacks in Paris. Several terrorist attacks in Paris, France, have left at least 129 dead and 350 injured. Most people were killed during a concert in venue Bataclan, the other targets were a restaurant and a soccer game. The attacks have been claimed by Islamic State. AFP PHOTO/BELGA/DIRK WAEM =BELGIUM OUT= (Photo credit should read DIRK WAEM/AFP/Getty Images)

Police officers man a cordon as an operation takes place in the Molenbeek district of Brussels on November 16, 2015. Belgian police launched a major new operation in the Brussels district of Molenbeek, where several suspects in the Paris attacks had previously lived, AFP journalists said. Armed police stood in front of a police van blocking a street in the run-down area of the capital while Belgian media said officers had surrounded a house. Belgian prosecutors had no immediate comment. AFP PHOTO / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)

Police officers man a cordon as an operation takes place in the Molenbeek district of Brussels on November 16, 2015. Belgian police launched a major new operation in the Brussels district of Molenbeek, where several suspects in the Paris attacks had previously lived, AFP journalists said. Armed police stood in front of a police van blocking a street in the run-down area of the capital while Belgian media said officers had surrounded a house. Belgian prosecutors had no immediate comment. AFP PHOTO / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)

Belgian police cordon off a street during a police raid in connection with the November 13 deadly attacks in Paris, in Brussels' Molenbeek district on November 14, 2015. Several people were arrested in Brussels on November 14 during police raids connected to the attacks in Paris, Belgian Justice Minister Koen Geens said. Geens said on RTBF television that these arrests in the capital's Molenbeek neighbourhood 'can be seen in connection with a grey Polo car rented in Belgium' found near the concert hall in the French capital where scores of people were killed. AFP PHOTO / BELGA / JAMES ARTHUR GEKIERE = BELGIUM OUT = (Photo credit should read JAMES ARTHUR GEKIERE/AFP/Getty Images)

A car is towed during a police raid in Brussels' Molenbeek district on November 14, 2015, in connection with the November 13 deadly attacks in Paris. Several people were arrested in Brussels on November 14 during police raids connected to the attacks in Paris, Belgian Justice Minister Koen Geens said. Geens said on RTBF television that these arrests in the capital's Molenbeek neighbourhood 'can be seen in connection with a grey Polo car rented in Belgium' found near the concert hall in the French capital where scores of people were killed. AFP PHOTO / BELGA / JAMES ARTHUR GEKIERE = BELGIUM OUT = (Photo credit should read JAMES ARTHUR GEKIERE/AFP/Getty Images)